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@tutti @with Lehm Parent No. loectedtwd .my 5,1870.

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The Schedule refen'mto in these Letters Patent and Amaking' peut of the stime.v

To 'all whom it may concern iBe it known that I, Annnr G. Horounrss, of'

.Wolcott-ville, in the county of Litchfield and State 0f Connecticut, have invented and made n new and useiiil Improvement in Tools for Boring; and the followng is hereby declared to bea correct description of the same.

Heretofore boring-toolslmve been made with n oenter-pin or bit to pass into `a hole that has been bored, and not as e guide to the cutter portion ofthe tool in boring n larger hole or countersiuk o u line with and :is o port-ion of the first hole. v

Boring-tools of this kind are usually made of one piece, and hence each tool has to` be made with specinl reference to the relative. sizes ofthe and second portionsA of the hole to be'formed.

My invention is made with reference to the use of one cutting-tool for enlarging the holeto a given size from :my size of hole that may have previously been v bored; and this I effect by providing remomble ceu ter-pins or bits of varying' diameters, but having n. uniform-sized shank to set into n hole in the boringv cutter, so that, within certain specitied ranges in the relative sizes of the cutters and centerfpins, they msi/y be used interchangeably, and thus a hole may be enlarged hyusing the corresponding-sized center-pin in n cutter oi' any size required fo'r the desired enlargement.

This interchangeable feature of the center-pin und horingltccl-is limited to the proper proportions for oo taining the necessary strength of centenpir.- compared with the size of cutter to he guided thereby My enti-er is constructed so as to he much more easily sharpened and kept in criertiinn-the cutters or boring-tools heretofore made with a, centra-l guiding-pin, because, sharpening the toni, the guidingpin is removed, and the face ot' the cutter is unobstructed, so thnt the edge can be sharpened from emi to end, one end o' the cutting-.edge being nt the hole for the centerplug, and the other cud at the periph-r -ery of the cutter.

In the rirnwiog- Figure 1 is nu elevation ct' the cutter complete;

Figure 2 is section of the tool as in use for horing an enlargement'ot the previously-bored hole; and

Figure 3 is un end view of the cuttenwithout the center-pin or bit.

The cutting-tool is made witha. socket, et, for receiving the tapering `end of the stem or stock b; and from the lower part of the socket a the cutting-edges c c project. l

' lhesc cutting-edges are mede at the 'proper ongle,

vthetzoes 2 being at. e backward inclination, and tlie lower fnces 3 being inclined upwhrd and backward' from the cutting-edges, so that the tool can be sharpened by grinding the faces 3; and this can bedone' ieely when the center-pin is removed from the tool.

The stock bis provided with a. key, 4, entering a. slot in the socket a, so that the parts will-'turn tc,- get-her. The center-pins :tre mode with bcdy-portions, e, ond Shanks, f1 l The Shanks j in the vnrions centenpins are all of the some size, but the body-portions e are of different sizes in the different center-pins.

I providein ezt-ch set of boring-tools r, given number of cutters of sizes varying -from one given 'nieasurement for the smallest cutter up to 'another measurement as the largest cutter.

` I also provide the requisite number of center-pins,

of sizes adapted to the set of cutters; and, as any center-pins can he usedwith J(my cutter -in the set,

any desired enlargement within the cztpaoityof the set can -be inode by selecting the proper center-pin and cutter, and placing them together.

` I claim es my inventionv l The improved tool herein described, consisting of the cutter-head a o, stock b, and'smooth cylindrical center-pin ej; substnntiallyns and for the purposes set forth.

Signed this 28th dey of January, A. D. 1870,

.ffiLBER'ilv G. HTCHKISS.

Witnesses:

Jos. S. Besancon, nbmr. BARBDUR. 

